With the development of communication technologies, 3G (3rd-Generation, the third generation mobile communication technology) technologies is widely used in wireless communication systems. At present, all 3G wireless communication systems use multiple carrier waves to achieve expansion of cells. In the multi-carrier wave cells, the multi-carrier wave signals that need to be transmitted perform linear superposition and combinations in the digital intermediate frequency section, and share a common set of transmitters to transmit, therefore, the transmitting end of the antenna appears higher PAR (Peak to Average Ratio) signals, and this requires the power amplifier to have larger linear regions, thus leading to lower efficiencies of the power amplifier, and then causing increased cost of the power amplifier. In view of the problems, in wireless communication systems, it usually adopts the peak clipping technology to reduce PAR of the signals which enter the power amplifier.
A conventional peak clipping mode includes: for a multi-carrier wave configuration, firstly, a prototype filter which matches the spectrum of a single carrier wave is designed, and according to the carrier wave frequency configuration, move the frequency domain of the prototype filter onto the center frequency point of each carrier wave, then add up to obtain a multi-carrier wave filter. Further, the prototype filter is set to be b(n), wherein, n=0, . . . , N−1, and N is the length of the peak clipping coefficient, while the prototype filter b(n) is able to be pre-generated and pre-stored, and obtained from the firls function of Matlab and using kaiser Adding Windows. Set the generation of the multi-carrier wave peak clipping coefficient to h(n), wherein, n=0, . . . , N−1, and N is the length of the peak clipping coefficient, and generate the multi-carrier wave peak clipping coefficient which meets the requirements of the carrier wave according to the carrier wave configuration frequency, and the generation method is as shown in the following formula:
      h    ⁡          (      n      )        =            b      ⁡              (        n        )              ⁢                  ∑                  k          =          1                I            ⁢              ⅇ                  j2          ⁢                                          ⁢                      π            ⁡                          (                              n                -                                  floor                  ⁡                                      (                                          N                      2                                        )                                                              )                                ⁢                                                    f                i                            ⁡                              (                k                )                                      /                          f              s                                          
In the formula above, the number of the carrier waves is I, fi(k) (1≦k≦1) is the ith carrier wave frequency, fs is the sampling frequency, and floor indicates rounding down. After the peak clipping coefficient is generated through the above process, it is capable to use the peak clipping coefficient to perform the peak clipping process on the multi-carrier wave signals.
However, the peak clipping coefficient obtained in this way is too complex, and each peak clipping coefficient is obtained by adding up multiple basic prototype coefficients, making EVM (Error Vector Magnitude) of the signal increased after the peak clipping. Especially, in the conventional technologies, with the increment of number of earlier waves and the expanding of frequency band, the system bandwidth needed is wider and wider, and at that moment, the added up prototype coefficients are more, the calculation of the peak clipping coefficient is also more complex, thus making EVM of the signal even more serious after the peak clipping, and then causing the signal distortion more serious.